wrapper/random.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * wrapper/random.c
   4  *
   5  * wrapper around bootid read. Using KALLSYMS to get its address when
   6  * available, else we need to have a kernel that exports this function to GPL
   7  * modules.
   8  *
   9  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  */
  11
  12 #include <linux/errno.h>
  13
  14 /* boot_id depends on sysctl */
  15 #if defined(CONFIG_SYSCTL)
  16
  17 #include <wrapper/fs.h>
  18 #include <linux/file.h>
  19 #include <linux/sched.h>
  20 #include <linux/uaccess.h>
  21 #include <wrapper/random.h>
  22
  23 /*
  24  * Returns string boot id.
  25  */
  26 int wrapper_get_bootid(char *bootid)
  27 {
  28         struct file *file;
  29         int ret;
  30         ssize_t len;
  31
  32         file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
  33         if (IS_ERR(file))
  34                 return PTR_ERR(file);
  35
  36         len = lttng_kernel_read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
  37         if (len != BOOT_ID_LEN - 1) {
  38                 ret = -EINVAL;
  39                 goto end;
  40         }
  41
  42         bootid[BOOT_ID_LEN - 1] = '\0';
  43         ret = 0;
  44 end:
  45         filp_close(file, current->files);
  46         return ret;
  47 }
  48 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  49
  50 #else
  51
  52 int wrapper_get_bootid(char *bootid)
  53 {
  54         return -ENOSYS;
  55 }
  56 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  57
  58 #endif